1. Field of the Invention
The present invention relates to a touch panel with which information is inputted by touching the panel with a finger or the like and to a display device having the touch panel.
2. Description of the Related Art
Recently, a display device with a touch panel acquired by combining the touch panel to a display input device such as a ticket-vending machine is being broadly put into practical use. With the display device having the touch panel, buttons to be touched are displayed on the display device. When those parts are pressed by a finger or the like, the fact that it is being pressed is detected and information is inputted. Further, the display device switches the image to be displayed based on the inputted information and executes a next input or other actions.
For such display device having that type of touch panel, not only the high definition of the display but also the high precision for detecting a touch input is required. Thus, there has been an increasing demand for taking a measure for the noise so as to prevent malfunctions and the like of touch signals.
Japanese Unexamined Patent Publication 2010-218542 (FIG. 1 and FIG. 10) (Patent Document 1) discloses a technique for providing a shield electrode in the outer periphery of the touch panel (referred to as “related technique 1” hereinafter) as a measure taken for the noise in a capacitance type touch panel. FIG. 29 shows the touch panel of the related technique 1, in which FIG. 29A is a plan view and FIG. 29B is a sectional view taken along a line X-X′ of FIG. 29A. Hereinafter, explanations will be provided by referring to those drawings.
In a touch panel 101 of the related technique 1, a detection region 104 is provided on a surface 103 of a substrate 102, and a wiring region 106 is provided on the outer side of the detection region 104. A plurality of detection electrodes 105 electrically isolated from each other for detecting existence of a conductor are formed in the detection region 104. A wiring electrode 107 electrically connected to the detection electrodes 105 and transmits a detection signal is formed in the wiring region 106. Further, a shield electrode 108 for shielding a noise intruded from outside is formed on the outer side of the detection region 104 and the wiring region 106, i.e., on the outer periphery of the substrate 102. In a case where other terminals or elements are disposed at the end part of the substrate 102, the shield electrode 108 may be formed by excluding such part where the terminals or elements are disposed. However, while the shield electrode 108 may be provided by being missed out partially as described above, the shield electrode 108 needs to be formed roughly about 70% or more of the entire outer periphery of the substrate 102.
Further, Patent Document 1 also discloses a technique which provides a conductive frame in addition to the shield electrode to the outer periphery of the touch panel (referred to as “related technique 2” hereinafter) as a measure taken for the noise in a capacitance type touch panel.
FIG. 30 is a sectional view showing the touch panel and the display device of the related technique 2. Hereinafter, explanations will be provided by referring to the drawing.
A touch panel 101 of the related technique 2 is almost in a same structure as that of the touch panel of the related technique 1. A detection region 104, a wiring region 106, a shield electrode 108, and the like are formed on a substrate 102. Further, underneath the touch panel 101, a liquid crystal display device 120 as the display device is provided. The liquid crystal display device 120 includes a liquid crystal panel 121, a translucent shield electrode 122, a light-shielding shield electrode 123, a conductor 124, a polarization plate 128, and the like. Further, from the above the shield electrode 108 and the wiring region 106, a conductive frame 127 is provided by surrounding a side-face outer periphery part 113 of the touch panel 101 and a side-face outer periphery part 125 of the liquid crystal display device 120. The related technique 2 is designed to further shield the electromagnetic noise and the static electricity for the touch panel 101 by providing the conductive frame 127 in addition to the shield electrode 108.
However, there are following issues regarding the related technique 2.
With the related technique 2, the wiring region 106 is provided on the outer side of the detection region 104, the shield electrode 108 is further provided in the outer periphery thereof, and the conductive frame 127 is provided above the wiring region 106 and the shield electrode 108. Thus, when a force by a finger or the like is applied and the conductive frame 127 is deformed, the distance between the conductive frame 127 and the wiring region 106 is changed so that the capacitance between the wiring region 106 and the conductive frame 127 is changed. This change in the capacitance becomes the noise of the touch signal flown in the wiring region 106, i.e., the noise of the detection signal.
That is, the shield electrode 108 is provided on the outer side of the wiring region 106 with the related technique 2, so that the distance from the detection region 104 to the shield electrode 108 becomes longer than the distance from the detection region 104 to the conductive fame 127. Thus, when a noise generated due to deformation of the conductive frame 127 is generated on the inner side than the shield electrode 108, i.e., on the detection region 104 side and the wiring region 106 side, the noise cannot be shielded by the shield electrode 108.
It is therefore an object of the present invention to provide a touch panel capable of shielding the noise generated due to deformation or the like of the conductive frame and to provide a display device having such touch panel.